Apparatus for electrical etching



March 16, 1937. i L. E. HOLLAND v 2,074,220

- APPARATUS FOR ELECTRICAL ETCHING Filed Nov. 23, 1933 4 Sheets-Sheet l46 47 24 IIIIUIV I lill uli INVENTOR ATTRNEY March 16, 1937. E. HOLLANDY 2,074,220

APPARATUS FOR ELECTRICAL ETCHING Filed Nov. 25, 1935 4 Sheets-Sheet 2 lINVENR 0 5 HaHa/7d. Y l l ATTRNEY March 16, 1937. L E. HOLLAND 2,074,220

APPARATUS FOR ELECTRICAL ETCHING Filed Nov. 25, 195s 4 sheets-sheet s 97-.54 /00 96 V 3/ 33 2? 3 y L l 5;'- 95,67 553 'famili 19' 5' 2 5 o o o 04/ 8 G I 1 42 r: /6

I I 7| H I. 'umh jg 3J, Il F l 6 C Il I INVENTOR 0a/5 Ho//and BY ATTORNEY March 16, 1937. E. HOLLAND APPARATUS FOR ELECTRICAL ETCHING FiledNOV. 23, 1953 INVENTOR L0 E. /o//and ATTRNEY Patented Mar. 16, 1937UNITED STATES PATENT OFFICE 8 Claims.

My invention relates to an apparatus for electrical etching.

In electrical etching as heretofore practiced, it

has been customary to immerse a plate to be- 5 etched in a bath ofelectrolyte and pass current through the plate and bath to a cathode,also immersed in the electrolyte, so that portions of the plate exposedto the electrolyte are dissociated from the plate to produce `,theetching; the plate 0 in some instances being reciprocated in ahorizontal plane within the bath to wash particles of metal, dissociatedfrom exposed portions of the plate by the electrochemical action, fromthe plate to speed up the operation and produce more regular lines ofetching.

I have discovered that by agitating the electrolyte relative to theplate, particularly with a jetting action, washing of the dissociatedparticles from the plate and removal of such particles from the regionof the plate is facilitated and, because of such constant exposure ofthe surface to be etched to clean electrolyte, thus further reducing thetime required for the etching operationand improving quality of theplate, and that rapid, effective removal of the dissociated particles ispromoted by tilting `of the plate reversely to flow of the electrolyteto provide more direct contact of the electrolyte with the surface to beetched.

It is, therefore, the object of my invention to provide the improvedmethod of etching last above described, and improved apparatus for-usein practicing the method.

In accomplishing such objects I have provided improved details ofstructure, the preferred form of which is illustrated in theaccompanying drawings, wherein:

Fig. 1 is a perspective view of apparatus embodying my invention andwith which my improved method may be practiced.

Fig. 2 is a similar view, showing the plate and plate holders removedfrom the tank.

Fig. 3 is a plan View of the apparatus, a part of the tank `and agitatorbeing broken away for better illustration, and the motor-generator guardbeing broken away to illustrate the drivingconnection between the motorand generator.

Fig. 4 is a central longitudinal section on the Fig. 5 is a similarlongitudinal section, the agitator and plate being shown at thecompletion of their stroke.

Fig. 6 is a transverse sectionon the line 6 6. Fig. 3;

Fig. 'l is a detail perspective view of a preferredform of plate hangerarm. l

Fig. 8 is a central transverse section of th hanger arm.

Fig. 9 is anelevation of the back of the hanger ,w

arm.

Fig.' 10 is a cross sectional view of the hanger arm on the linelll-IIJ, Fig. 8.

Fig. 11 is an enlarged detail perspective View of the clamp cam memberof the plate hanger 15 arm.

Fig. 12 is an enlarged sectional View of a lower corner of the tank,particularly illustrating' the wall construction.

Fig. 13 is a wiring diagram.

Referring more in detail to the drawings:

I designates a bench adapted for supporting an etching tank at aconvenient elevation, preferably constructed of legs 2, tie rods 3,longitudinal sills 4 and cross sills 5, t, the latter inset from 25 oneend of the bench to provide space for support of the base 1 on which amotor 8 and generator 9 may be mounted conveniently to an etching tankI0, removably supported on the cross sills 5, 6, to form a compactapparatus unit. 30

The tank I0 is preferably of improved con-f struction consisting ofintegral side, end and vbottom walls l Il, Il! and i3, formed of castiron or other conductive material, with the bottom formed to providealternate, transverse, raised, 35 plate-like sections M and connectingsumptrough sections I5, the latter terminating at the sides of the tankin a trough lli extending entirely about the bottom of the tank, intowhich the sump troughs may empty for drainage of the electrolyte throughan opening l'l normally closed by a screw plug It. The entire exteriorand interior `surfaces of the side and end walls of the tank, the sumptroughs l5 and the drain 45 trough I6 are lined with non-corrosivematerial, such as porcelain, to protect the body of the tank from attackby the electrolyte, but the upper surfaces of the transverse, plate-likeportions M of the tank body are unlined to expose such surfaces to theelectrolyte so that they may constitute cathodes, as hereinafterdescribed.

Terminal posts |9 are extended through the exterior lining to contactwith the cathode plates, and provided at their outer ends with bus bars28, with which the negative lead wires 2| of an electrical circuit areconnected by clips 22.

Mounted on the rims 23 of the side walls of the tank are'brackets 24carrying rollers 25, having grooves 26 within which ride the side rails21 of an agitator supporting frame 28 of rectangular construction,including end rails 29 riveted or otherwise secured to the side rails 21and braced therefrom by corner strips 30, the end rails 29 being locatedwell within the extended planes of the end walls of the tank to permitreciprocation of the agitator which is suspended from said end railsWithin the tank, as presently described.

Reciprocation of the frame 28, and the agitator suspended therefrom, iseffected preferably by a pair of levers 3| fulcrumed on pins 32 attachedto the cross sills 5, 6, and having slots 33 at their upper ends seatingpins 34 projecting in alignment from opposite side rails 21 of theagitator supporting frame; the lower ends of the levers being connectedwtih a cross rod 35 on a crank arm 36 operable from a motor 31,suspended below the tank by brackets 38, attached to the bottom of thetank by stud bolts 39, through speed reduction gearing, such as a Wormshaft and wheel indicated by the housing 48.

The agitator proper includes a rectangular frame 4| formed of side rails42 and end rails 43 suspended from the reciprocatory frame 28 by hangersincluding strips 44 attached to and depending from the end rails 29 offrame 28, and strips 45 attached to the end rails 43 of the agitatorframe, overlapping corresponding strips 44 on the supporting frame andadjustably connected thereto by bolts 46 having head portions 41slidable in slots 48 in the strips 44 and nuts 49 adapted for bearingagainst the inner faces of the strips 45 to` tighten the strips 45against the strips 44; the strips 45 being preferably provided withguides 58 for confining the strips 44 and assisting the thumb bolts inholding the adjustable strips in rigid relation.

Extending transversely between the side rails 42 of the agitator frameand secured thereto are blades 5| arranged in pairs, with the members ofeach pair converging upwardly but spaced apart to provide elongatedtransverse. jet openings 52; the lower edges of the bars of adjacentpairs being likewise spaced to form bottom openings 53, whereby uponreciprocation of the agitator within the electrolyte contained within'the tank, the electrolytic liquid will be delivered up-v wardly inelongated jets and angularly in a direction dependent upon direction ofthe movement of the agitator.

Mounted centrally on the rims 23 of the side walls of the tank arebrackets 54 inset from the side rails 21 of the agitator supportingframe 28 to avoid interference therewith, and adapted for pivotallymounting a plate supporting frame 55, as hereinafter described.

The plate supporting frame 55 is preferably formed of strap metal withthe sides 56 and ends 51 arranged edgewise and the side members providedwtih trunnions 58 rotatably mounted in the brackets 54 on the tank rim;collars 59 (Fig. 6) spacing the side members from the brackets; Washers68 providing additional bearing surface for the trunnions and thetrunnions being locked to the brackets by nuts 6|.

Extending inwardly from the lower edge of each of the end members 51 isa flange 62 having spaced bosses 63 on its upper face for selectivelyseating hanger rods 64 from which the plate hangers 65 are suspended.Each of the hangers 65 preferably includes a strip 66 of conductivematerial, such as copper, having a hook 61 at its upper end adapted tofit over one of the rods 64 and provided at its lower end with anextension 68 of reduced width adapted to fit within a longitudinalgroove 69 in a body member 18 of ber or other non-conductive material,having a laterally extending shelf 1| at its lower end and a slot 12immediately above the shelf through which a lip 13 on the extension 68is projected to overlie the shelf.

The extension 68 of strip 66 is preferably formed of silver because ofthe highly conductive and non-corrosive qualities of such metal, and inorder to avoid expense of construction of the entire strip from the moreexpensive material.

Lying against the face of the body strip 18 opposite the conductor strip66 is a clamp strip 14 adapted for adjustment on the body strip by a pin15 extending through a slot 16 for retaining the clamp strip on the bodystrip and having a head 'l1 for retaining the clamp strip on the bodystrip, and a cam member 18 having a shank 19 rotatable in apertures 88and 8| in the body and conductor strips, and an eccentric head 82mounted in a circular aperture 83 in the clamp strip; the cam pin beingretained on the hanger by a cotter pin 84 at one end and a head 85 atthe other end provided with a handle 86, whereby the pin may be rotatedto move the clamp strip longitudinally for thrust against a plate 81seated on the lip 1| of the conductor strip and to release the plate bymovement of the clamp strip in the opposite direction.

Extending through the upper end of the body strip 18 to conductiverelation with the conductor strip 66 is a terminal post 88 preferablyattached to the conductor strip by riveting as at 89, and having a head98 at its outer end. Fixed to the post 88 in contact with the body stripis a washer 9|, and slidable on the post at the outside of the washer'Slis a second washer 92 urged toward the first by a coil spring 93.bearing against the washer 92 and against a washer 94 retained on thepost by the head 98; the washers 9| and 92 being of conductive materialand adapted to receive the slotted clip 95 of a circuit wire 96therebetween when the washers are spread by projection of the clip overthe post and between the washers against the tension of the spring 93. I

The hangers 65 are arranged in pairs on the respective rods 64 forsupporting the plate to be etched at its four corners; adjustability ofthe rods on the frame 55 and of the hangers 65 on the rods adapting suchelements for support of plates of diiferent dimensions within the tank.

The frame 55 is rockable to alternately tilt the suspended plate inopposite directions by means of an arm 91 attached to one of the siderails of the frame, and having a cam slot 98 in which a pin 99 on a siderail of the agitator supporting frame is projected, so that when theagitator supporting frame is reciprocated the pin moves through the slotand effects a rocking action of the plate supporting frame.

The wires 96, through which current is supplied to a plate immersed inthe etching solution,

run through a conduit mounted on the bench to series connection with thegenerator circuit |0| including a switch |02, .a voltmeter |03, an

`ammeter |04 and a rheostat |05, all mounted on a switch board |06attached to the bench and. extending alongside the treating tank. Themotor 31 for operating the reciprocating agitator and rocking platehanger frames is operated through a `circuit |01 tapped into the leadwires |08, |09, of a lighting or other circuit from which current isdrawn for operating the gene ator motor 8; the small motor circuithaving a swtch |0 and rheostat also mounted on the switch board |06, sothat all of the electrical controls are in convenient reach of theperson conducting the etching operation. The generator illustratedvis-self-excited but could be separately excited wihout altering itsfunction.

The tank '|0 is provided with a skirt ||2 for protecting the motor andgenerator from solution that may be splashed from the tank, the

conduit |00 for the positive lead wires 96 being provided with a rack||3 for suspending said wires out of the way of the operator whendisconnected from the plate hangers, and other details of structure forconvenience in operation ofv the apparatus, but not necessarily includedin the invention, may be included in the apparatus.

The etching solution may be of any formula known in the art.

Assuming the parts of the apparatus to be constructed as described, withthe tank and its directly connected parts, the motor and generatorassembled on the bench and the tank filled to a desired depth withsuitable etching solution, a

plate to be etched is assembled on its hangers,

the hanger supporting rods selectively positioned on their frame and theplate suspended in the solution by application of the hangers to therods. The positive wires`96 are then conductively connected with thehangers by projection of their clips between the washers of the socketson the hangers and the apparatus placedin operation by throw of thesecondary motorA and generator switches. Current then passing throughthe solution from the plate, acting as an anode, to the exposedprotuberances of the bottom of the tank, acting as cathodes, energizesthe solution to yconstitute it an electrolyte.

This electrolyte, acting on exposed surfaces of the plate, decomposessuch exposed surfaces, and as thel agitator moves back and forth beneaththe plate the electrolyte is washed against the platewith a jet actioninduced by the angling bars that extend transversely between the railsof the agitator frame, thereby flushing the decomposed material from theexposed surfaces and y removing such material from the etching area sothat constantly fresh electrolyte is applied to the plate withoutinterference from the removed decomposed particles.

Simultaneously with reciprocation of the agitator the plate is tiltedfirst in one direction and then in the other so that as the agitatormoves forwardly relatively to the plate, the jets induced by theagitator may have more direct contact with the plate than if the latterremained stationary and in a plane parallel with the agitator. Thematerial dissociated from the plate falls by grav-l ity through theagitator into the sumps in the bottom of the tank and passes from thesumps into the side troughs so that substantially pure electrolyte isconstantly available for application to the plate. l

I have found that by thus agitating the solution to wash the plate amuchmore rapid and cleaner etching is effected than by movement of the platethrough the solution, and that the time and quality factors are enhancedby jetting of the solution and tilting of the plate, whereby the morepositive and direct application of the solution to` the plate andremoval of dissociated particles from the region of the plate lseffected.

What I claim and desire to secure'by Letters Patent is:

1. Apparatus of the character described including a tank for containingelectrolyte, means for supporting a plate to be etched submerged facedownward in the electrolyte, means for moving said plate supportingmeans to vary angular positions of the plate, means for passing anelectrical current through the plate and electrolyte to eectdissociation of particles from the plate, a plurality of blades mountedfor reciprocation beneath the plate, and means for recipro'cating theblades for agitating the electrolyte and washing dissociated particlesfrom the plate.

2. Apparatus of the character described including a tank for containingelectrolyte, means for holding a plate to be etched submerged in theelectrolyte, means for passing an electrical current through the plateand electrolyte to effect dissociation of particles from the plate, andmeans l wardly converging blades carried by the frame and an actuatorfor reciprocating the frame.

4. Apparatus of the character described includving a tank for containingelectrolyte, reciprocatory and rockable frames mounted on the tank,means on the rockable frame for supporting a plate within the tank, anagitator 'suspended from the reciprocating frame, and cam connectionlbetween the frames for reversing inclination of a plate carried by therocking frame coincidently with change' of direction of travel of theagitator. f

5. Apparatus of the character 'described lncluding a tank for containingelectrolyte, means for holding a plate to be etched submerged in theelectrolyte, means for passing an electrical current through the plateand electrolyte to effect dissociation of particles from the plate, anagitator 'mounted for reciprocationl adjacent the L plate, means forreciprocating the agitator for agitating the `electrolyte and washingdissociated particles from the plate, and means for tilting the platerelative to the agitator in response to reciprocation of said agitator.

.6. Apparatus of the character described including a tank, means forsupporting a plate to be etched within an electrolyte contained by thetank, and a, member reciprocable in the electrolyte in a pathsubstantially parallel with the plate, including blades inclined to thepath of said member for directing currents of the electrolyte toflushing contact with the plate in response to reciprocation of saidmember in the bath.

7 Apparatus of the character described includ--Y ng a tank, means forsupporting a plate to be etched within an electrolyte contained by thetank, and a member reciprocable in the electrolyte in a bathsubstantially parallel with the plate, including a plurality of seriesof pairs of blades, the blades of each pair converging in the directionof the plate and spaced to provide jet openings for directing currentsof the electrolyte toi flushing contact with the plate in response torel0 'ciprocation of said member in the bath.

8. Apparatus of the character described includ- LOUIS E. HOLLAND.

